This invention relates to blade sharpeners and more particularly to portable units which are hand held and on which the sharpening angle is pre set.
There are many portable blade sharpeners on the market today. All of them allege certain advantages over their competition and it is very likely true that a specific type of sharpener might well be an excellent device for a single function. What is needed is a portable blade sharpener which will be universal in nature so as to provide wide utility in the blade sharpening field.
One of the most interesting patents with respect to the present invention is Longbrake U.S. Pat. No. 3,819,170 issued June 25, 1974 entitled "Portable Sharpener". In this patent the guide bracket has a plurality of holes adapted to receive a rod connected to the abrasive stone. Obviously the height of the hole in the bracket determines the sharpening angle. Unfortunately the geometry of this arrangement is such that the true desired angle can only be acheived by straight back and forth movement of the stone over the blade. If the stone pivots substantially to either side of the guide bracket the desired angularity is changed.
The problems of pivoting a sharpening stone and yet maintaining the desired sharpening angle is dealt with in Brougher U.S. Pat. No. 1,750,504. This problem is handled by making certain that the rack 18 which meshes with pinion 17 is concentric with the pivot 13. Thus the distance is always the same and angularity is constant.
In view of the foregoing, it is an object of this invention to provide a portable sharpening device which has a minimum number of parts without losing any of its functional characteristics.
It is another object of this invention to provide a portable sharpening device capable of being used to sharpen scissors and bladed devices such as knives.
It is yet another object of this invention to provide a portable blade sharpening device wherein the guide bracket will provide movement over substantially the length of the blade while still maintaining the desired angle.
The above and additional objects and advantages will become more apparent when taken in conjunction with the following detailed description and drawings showing preferred embodiments of this invention.